Authors

A. Dhingra; A. R. Portis;H. Daniell

Comments

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Abbreviated Journal Title

Proc. Natl. Acad. Sci. U. S. A.

Keywords

RIBULOSE-1, 5-BISPHOSPHATE CARBOXYLASE/OXYGENASE RUBISCO; TOBACCO; CHLOROPLASTS; PLASTID GENOME; PROTEIN; ARABIDOPSIS; GROWTH; PSBA; FORM; TRANSFORMATION; MODULATION; Multidisciplinary Sciences

Abstract

Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) is a key enzyme that converts atmospheric carbon to food and supports life on this planet. Its low catalytic activity and specificity for oxygen leads to photorespiration, severely limiting photosynthesis and crop productivity. Consequently, Rubisco is a primary target for genetic engineering. Separate localization of the genes in the nuclear and chloroplast genomes and a complex assembly process resulting in a very low catalytic activity of hybrid Rubisco enzymes have rendered several earlier attempts of Rubisco engineering unsuccessful. Here we demonstrate that the RbcS gene, when integrated at a transcriptionally active spacer region of the chloroplast genome, in a nuclear RbcS antisense line and expressed under the regulation of heterologous (gene 10) or native (psbA) UTRs, results in the assembly of a functional holoenzyme and normal plant growth under ambient CO2 conditions, fully shortcircuiting nuclear control of gene regulation. There was approximate to150-fold more RbcS transcript in chloroplast transgenic lines when compared with the nuclear RbcS antisense line, whereas the wild type has 7-fold more transcript. The small subunit protein levels in the gene 10/RbcS and psbA/RbcS plants were 60% and 106%, respectively, of the wild type. Photosynthesis of gene 10/RbcS plants was approximately double that of the antisense plants, whereas that of psbA/RbcS plants was restored almost completely to the wild-type rates. These results have opened an avenue for using chloroplast engineering for the evaluation of foreign Rubisco genes in planta that eventually can result in achieving efficient photosynthesis and increased crop productivity.

Journal Title

Proceedings of the National Academy of Sciences of the United States of America

Volume

101

Issue/Number

16

Publication Date

1-1-2004

Document Type

Article

Language

English

First Page

6315

Last Page

6320

WOS Identifier

WOS:000220978000113

ISSN

0027-8424

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